Lockheed Martin Corporation

Loral Vought Systems Corporation

Lockheed Martin Vought Systems Corp.

Austin J Brouns

Thomas R Schimert

James H McCurdy

Thomas A Shafer

A photodetector for detecting the polarization or wavelength of incident infrared radiation (IR) is described. The polarization sensitive photodetector operates using two sets of patches and corresponding cavities, the first set resonating with IR having a first polarization, while the second set resonates with IR having an orthogonal, second polarization. The polarization sensitive photodetector thus outputs two signals, proportional to the first and second polarizations, respectively. The wavelength sensitive photodetector operates using two sets of patches and corresponding cavities, the first set resonating at a first IR wavelength, while the second set resonates at a different IR wavelength. The wavelength sensitive photodetector thus outputs two signals, proportional to the first and second wavelengths, respectively. The patches have a length corresponding to odd multiples of the effective wavelength of the IR, while the thickness of the photodetector is typically one fourth of the effective wavelength.

Polarization and wavelength-selective patch-coupled infrared photodetector

A photodetector for detecting infrared radiation (IR) using a slab waveguide is described. The slab waveguide photodetector operates by resonating transverse magnetic or electric modes within the slab from the incident IR. An IR absorbing layer is located within the slab waveguide photodetector where the magnitude of the electric field vector is greatest. This permits the use of a thinner IR absorbing layer without sacrificing photoresponse. Multi-color slab waveguide photodetectors are permitted because multiple transverse magnetic or electric modes resonate within the slab waveguide. A reflective or transmissive grating is used to launch the IR into the IR absorbing layer through a cladding or antireflection layer.

Photodetector employing slab waveguide modes

An infrared detector element includes a metallic patch which is positioned on the surface of an upper contact layer. A multiple quantum well ('MQW') infrared sensitive structure is positioned between the first contact layer and a second contact layer. The conductive contact layers are transparent to infrared radiation. A groundplane which is reflective to infrared radiation is positioned adjacent the second contact layer. A resonant cavity is formed between the metallic patch and the groundplane. The thickness of this cavity is not greater than approximately one eighth of the wavelength of the incident infrared radiation within the cavity. The metallic patch functions to couple the incident infrared radiation into the resonant cavity wherein the E-field is oriented substantially normal to the plane of the MQW structure. A plurality of the detector elements can be used to form a single pixel and an array of the pixels can be used to form a complete infrared radiation imager.

Patch coupled infrared photodetector

An apparatus (10) is provided for measuring the excess carrier lifetime in a semiconductor material, such as an HgCdTe wafer (MCT). The apparatus includes a computer controller (56) which automates the functions of the apparatus, including the operation of the shutter (28) to control the time the testing samples are exposed to the excitation energy from a laser (14), the laser energy intensity on the sample, the position of the wafer controlled by the computer controller operating a motorized sample positioner (39) and maintaining the temperature of the sample. Multiple samples are taken by the apparatus which are averaged and analyzed to result in a characterization of the carrier lifetime.

Growing community of inventors

Dallas, TX, United States of America

Austin J Brouns